Idle (the drive is not accessed at all, but it is turned on and ready to work)

Random Read and Write

Sequential Read and Write

Let’s check out each mode one by one.

The electronics of each HDD consumes about the same about of power from the 5V line when starting up. The WD RE4-GP with 64MB of buffer memory needs somewhat more than the others, though. The Seagate HDDs consume much more power from the 12V line than the others. Hopefully, they need such a high current only to speed the platters up faster.

When idle, the HDDs with lower spindle speed prove to be economical indeed. Even the worst of them is 2 watts better than the Seagate 7200.11. The Seagate LP must be noted again. Despite the somewhat higher rotation speed (in comparison with the other power-efficient models), it is in the top three in power efficiency, being but slightly worse than the two HDDs from Western Digital. We have only one question left: what are the other two HDDs from Western Digital doing if their 5V power consumption is two times as high as that of the other power-efficient HDDs?

The electronics don’t do much at random reading. It is the HDD’s mechanics that does most of the job. The 7200rpm model needs 1.5W of power more than the others and is proportionally hotter. The HDDs with slowed-down heads – the Western Digital AV-GP and the 1.5TB Caviar Green – have somewhat better results than the others.

Deferred writing algorithms come into play here. Consequently, the Seagate HDDs are better than the others in terms of 5V consumption, but worse in terms of 12V consumption. The Samsung is the overall winner. The WD RE4-GP is the worst drive here.

At sequential reading it is on the +12V line that we can see most differences. There are no winners but there are losers. There is one loser, actually. It is the old Seagate 7200.11 with high spindle rotation speed. It consumes 1.5W more than its opponents.

The sequential writing results are similar to those of the previous test. The HDD with higher spindle rotation speed loses again. We must note a couple of facts, though. The WD Caviar Green saves on the 12V line but consumes more than the others on the 5V line. The Seagate LP is good. Although it has a somewhat higher spindle rotation speed than the other power-efficient HDDs, its power consumption is more than modest.